This project emphasizes studies using newly emerging robust non invasive ultrasonic imaging technologies for quantifying structural and functional cardiovascular pathology. Using hydrodynamic principles, temporal and spatial aspects of cardiac structural abnormalities and pathophysiologic flow events are described and their quantification validated. In the clinical management of cardiac dysfunction, quantitatively accurate assessment is of major importance for diagnosis, prognosis and therapy. Non invasive assessment is, in addition, economically desirable. To these ends, the current year's efforts have extended previous years' studies to include: 1)An in vivo experimental study validated the feasibility of a newly developed dynamic 3D digital color Doppler technique for directly quantifying transmitral flow volume. 2) Real-time 3D echocardiographic imaging allowed rapid and accurate measurements of left ventricular volume and mass. 3) A digital color Doppler method using average values from two orthogonal planes provided accurate estimation of pulmonary regurgitant stroke volumes and regurgitant fractions, having clinical relevance for serially quantifying pulmonary regurgitation in patients with postoperative tetralogy of Fallot. 4)Continuous wave Doppler aortic regurgitant spectra provided a reliable noninvasive estimate of left ventricular dP/dt, being potentially helpful in the serial assessment of ventricular function in patients with aortic regurgitation. 5)Good correlation was observed between interaliasing distance of the flow convergence surface for determining mitral regurgitant volume and regurgitant volume determined by electromagnetic flow probes. 6)Quantification of aortic regurgitation by real-time 3D echocardiography in a chronic animal model was computed as the difference between left and right ventricular stroke volumes. These studies have been published or are in press. On-going imaging studies continue to include those using chronic animal models of aortic and mitral regurgitation, acute and chronic myocardial infarction and ventricular aneurysms.